Gas bag modules of this type are known from the prior art. They have the advantage that the gas bag, seen from the point of view of the occupant, initially presents a large impact surface instead of great depth. The large impact surface in many seating positions of the occupant assures very good restraint conditions. Moreover, the front wall, which moves towards the occupant, is slowed by the retaining element at an early point in time.
However, at especially high vehicle velocities or in the case of especially heavy occupants, it is possible that the available plunge depth needs to be increased. Therefore, thought has been given to destroying the retaining element in the course of the inflation process, so that the gas bag has greater depth and therefore the plunge path for an occupant is longer. Several passive and active approaches are familiar for detaching or destroying the retaining element.
Thus, for example, the retaining element can have a predetermined breaking point at which the retaining element ruptures as a function of the interior pressure of the gas bag. Passive solutions of this type that are realized through predetermined breaking points, tear seams, etc., are highly subject to tolerances. On the one hand, the tolerances are generated in manufacturing the predetermined breaking points or tear seams themselves, but they can also be generated in the discharging of gas generators. The other approach to detach or destroy the retaining element are active systems, in which cutting devices or attachment bolts of the retaining element are set in motion. These systems require an additional actuator and are therefore complicated and expensive.
The generic document EP 1 155 924 A2 discloses both active as well as passive approaches for detaching or destroying the retaining element. Among others, an embodiment is shown in which a catch strap extends through a diffuser and past the discharge openings of a gas generator. When the gas generator is activated, hot gas flows onto the catch strap, which is partially destroyed in the process. In this context, the disadvantage is that the destruction of the catch strap is directly coupled to the inflation process of the gas bag.
It is an object of the present invention to reliably and timeably bring about a destruction of a gas bag retaining element.